First iteration of the ssi routines

.gitignore

@@ -0,0 +1 @@
+.idea/

README.md

@@ -0,0 +1,73 @@
+# Helper routines to manage DIDs/VC/VPs
+
+This module is a wrapper around the functions exported by SpruceID's `DIDKit` framework.
+
+## DID generation and storage
+
+For now DIDs are of the kind `did:key`, with planned support for `did:web` in the near future.
+
+Creation of a DID involves two steps:
+* Generate a unique DID controller key
+* Derive a `did:key` type from the key
+
+Both must be stored in the IdHub database and linked to a `User` for later retrieval.
+
+```python
+# Use case: generate and link a new DID for an existing user
+user = request.user # ...
+
+controller_key = idhub_ssikit.generate_did_controller_key()
+did_string = idhub_ssikit.keydid_from_controller_key(controller_key)
+
+
+did = idhub.models.DID(
+    did = did_string,
+    user = user
+)
+did_controller_key = idhub.models.DIDControllerKey(
+    key_material = controller_key,
+    owner_did = did 
+)
+
+did.save()
+did_controller_key.save()
+```
+
+## Verifiable Credential issuance
+
+Verifiable Credential templates are stored as Jinja2 (TBD) templates in `/schemas` folder. Please examine each template to see what data must be passed to it in order to render.
+
+The data passed to the template must at a minimum include:
+* issuer_did
+* subject_did
+* vc_id
+
+For example, in order to render `/schemas/member-credential.json`:
+
+```python
+from jinja2 import Environment, FileSystemLoader, select_autoescape
+import idhub_ssikit
+
+env = Environment(
+    loader=FileSystemLoader("vc_templates"),
+    autoescape=select_autoescape()
+)
+unsigned_vc_template = env.get_template("member-credential.json")
+
+issuer_user = request.user
+issuer_did = user.dids[0]  # TODO: Django ORM pseudocode
+issuer_did_controller_key = did.keys[0]  # TODO: Django ORM pseudocode
+
+data = {
+    "vc_id": "http://pangea.org/credentials/3731",
+    "issuer_did": issuer_did,
+    "subject_did": "did:web:[...]",
+    "issuance_date": "2020-08-19T21:41:50Z",
+    "subject_is_member_of": "Pangea"
+}
+signed_credential = idhub_ssikit.render_and_sign_credential(
+    unsigned_vc_template,
+    issuer_did_controller_key,
+    data
+)
+```

idhub_ssikit/__init__.py

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+import asyncio
+import datetime
+import didkit
+import json
+import jinja2
+
+
+def generate_did_controller_key():
+    return didkit.generate_ed25519_key()
+
+
+def keydid_from_key(key):
+    return didkit.key_to_did("key", key)
+
+
+def generate_generic_vc_id():
+    # TODO agree on a system for Verifiable Credential IDs
+    return "https://pangea.org/credentials/42"
+
+
+def render_and_sign_credential(vc_template: jinja2.Template, jwk_issuer, vc_data: dict[str, str]):
+    """
+    Populates a VC template with data for issuance, and signs the result with the provided key.
+
+    The `vc_data` parameter must at a minimum include:
+        * issuer_did
+        * subject_did
+        * vc_id
+    and must include whatever other fields are relevant for the vc_template to be instantiated.
+
+    The following field(s) will be auto-generated if not passed in `vc_data`:
+        * issuance_date (to `datetime.datetime.now()`)
+    """
+    async def inner():
+        unsigned_vc = vc_template.render(vc_data)
+        signed_vc = await didkit.issue_credential(
+            unsigned_vc,
+            '{"proofFormat": "ldp"}',
+            jwk_issuer
+        )
+        return signed_vc
+
+    if vc_data.get("issuance_date") is None:
+        vc_data["issuance_date"] = datetime.datetime.now().replace(microsecond=0).isoformat()
+
+    return asyncio.run(inner())
+
+
+def verify_credential(vc, proof_options):
+    """
+    Returns a (bool, str) tuple indicating whether the credential is valid.
+    If the boolean is true, the credential is valid and the second argument can be ignored.
+    If it is false, the VC is invalid and the second argument contains a JSON object with further information.
+    """
+    async def inner():
+        return didkit.verify_credential(vc, proof_options)
+
+    return asyncio.run(inner())

main.py

@@ -2,6 +2,7 @@ import asyncio
 import didkit
 import json
 from jinja2 import Environment, FileSystemLoader, select_autoescape
+import idhub_ssikit
 
 jwk_issuer = didkit.generate_ed25519_key()
 jwk_subject = didkit.generate_ed25519_key()
@@ -10,12 +11,11 @@ did_issuer = didkit.key_to_did("key", jwk_issuer)
 did_subject = didkit.key_to_did("key", jwk_subject)
 
 
-async def main():
 env = Environment(
     loader=FileSystemLoader("vc_templates"),
     autoescape=select_autoescape()
 )
-    unsigned_vc_template = env.get_template("affiliation.jsonld.j2")
+unsigned_vc_template = env.get_template("member-credential.json")
 data = {
     "vc_id": "http://example.org/credentials/3731",
     "issuer_did": did_issuer,
@@ -23,11 +23,10 @@ async def main():
     "issuance_date": "2020-08-19T21:41:50Z",
     "subject_is_member_of": "Pangea"
 }
-    unsigned_vc = unsigned_vc_template.render(data)
+signed_credential = idhub_ssikit.render_and_sign_credential(
-    signed_credential = await didkit.issue_credential(
+    unsigned_vc_template,
-        unsigned_vc,
+    jwk_issuer,
-        json.dumps({"proofFormat": "ldp"}),
+    data
-        jwk_issuer)
+)
-    print(signed_credential)
 
-asyncio.run(main())
+print(signed_credential)

vc_templates/academic.jsonld.j2

@@ -4,7 +4,7 @@
 		{
 	    	"title" : "trustchain:title",
             "name": "trustchain:name",
-            "grade": "trustchain:grade"
+            "grade": "trustchain:grade",
             "date_earned": "trustchain:dateearned"
         }
 	],

vc_templates/member-credential.json

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+{
+  "@context": [
+    "https://www.w3.org/2018/credentials/v1",
+    {
+      "name": "https://schema.org/name",
+      "email": "https://schema.org/email",
+      "membershipType": "https://schema.org/memberOf",
+      "individual": "https://schema.org/Person",
+      "organization": "https://schema.org/Organization",
+      "Member": "https://schema.org/Member",
+      "startDate": "https://schema.org/startDate",
+      "jsonSchema": "https://schema.org/jsonSchema",
+      "$ref": "https://schema.org/jsonSchemaRef"
+    }
+  ],
+  "type": ["VerifiableCredential", "VerifiableAttestation"],
+  "id": "{{ vc_id }}",
+  "issuer": "{{ issuer_did }}",
+  "issuanceDate": "{{ issuance_date }}",
+  "credentialSubject": {
+    "id": "{{ subject_did }}",
+    "Member": {
+      "name": "{{ name }}",
+      "email": "{{ email }}",
+      "membershipType": "{{ membershipType }}",
+      "startDate": "{{ startDate }}"
+    },
+    "jsonSchema": {
+      "$ref": "https://gitea.pangea.org/trustchain-oc1-orchestral/schemas/member-schema.json"
+    }
+  }
+}

vc_templates/wikipedia.jsonld.j2

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+{
+    "@context": [
+        "https://www.w3.org/2018/credentials/v1",
+        "https://www.w3.org/2018/credentials/examples/v1"
+    ],
+    "id": "0892f680-6aeb-11eb-9bcf-f10d8993fde7",
+    "type": [
+        "VerifiableCredential",
+        "UniversityDegreeCredential"
+    ],
+    "issuer": {
+        "id": "{{ issuer_did }}",
+        "name": "Acme University"
+    },
+    "issuanceDate": "2021-05-11T23:09:06.803Z",
+    "credentialSubject": {
+        "id": "did:example:ebfeb1f712ebc6f1c276e12ec21",
+        "degree": {
+            "type": "BachelorDegree",
+            "name": "Bachelor of Science"
+        }
+    }
+}